pandoc-cli: Allow building a binary without Lua support

Disabling the `lua` cabal flag will result in a binary without Lua.

1 files changed, 26 insertions, 0 deletions

diff --git a/pandoc-cli/no-lua/PandocCLI/Lua.hs b/pandoc-cli/no-lua/PandocCLI/Lua.hs
new file mode 100644
index 000000000..350a4cdbc
--- /dev/null
+++ b/pandoc-cli/no-lua/PandocCLI/Lua.hs
@@ -0,0 +1,26 @@
+{-# LANGUAGE OverloadedStrings #-}
+{- |
+   Module      : PandocCLI.Lua
+   Copyright   : © 2022 Albert Krewinkel
+   License     : GPL-2.0-or-later
+   Maintainer  : Albert Krewinkel <[email protected]>
+
+Placeholder values to be used when pandoc is compiled without support
+for the Lua scripting engine.
+-}
+module PandocCLI.Lua (runLuaInterpreter, getEngine) where
+
+import Control.Monad.IO.Class (MonadIO)
+import Text.Pandoc.Error (PandocError (PandocNoScriptingEngine), handleError)
+import Text.Pandoc.Scripting (ScriptingEngine, noEngine)
+
+-- | Raises an error, reporting that the scripting engine is unavailable.
+runLuaInterpreter :: String    -- ^ Program name
+                  -> [String]  -- ^ Command line arguments
+                  -> IO ()
+runLuaInterpreter _progName _args = do
+  handleError (Left PandocNoScriptingEngine)
+
+-- | Placeholder scripting engine.
+getEngine :: MonadIO m => m ScriptingEngine
+getEngine = pure noEngine